1 files changed, 138 insertions, 0 deletions
diff --git a/indra/llcommon/lltempredirect.cpp b/indra/llcommon/lltempredirect.cpp
new file mode 100644
index 0000000000..ec194c1d29
--- /dev/null
+++ b/indra/llcommon/lltempredirect.cpp
@@ -0,0 +1,138 @@
+/**
+ * @file   lltempredirect.cpp
+ * @author Nat Goodspeed
+ * @date   2019-10-31
+ * @brief  Implementation for lltempredirect.
+ * 
+ * $LicenseInfo:firstyear=2019&license=viewerlgpl$
+ * Copyright (c) 2019, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "lltempredirect.h"
+// STL headers
+// std headers
+#if !LL_WINDOWS
+# include <unistd.h>
+#else
+# include <io.h>
+#endif // !LL_WINDOWS
+// external library headers
+// other Linden headers
+
+/*****************************************************************************
+*   llfd
+*****************************************************************************/
+// We could restate the implementation of each of llfd::close(), etc., but
+// this is way more succinct.
+#if LL_WINDOWS
+#define fhclose  _close
+#define fhdup    _dup
+#define fhdup2   _dup2
+#define fhfdopen _fdopen
+#define fhfileno _fileno
+#else
+#define fhclose  ::close
+#define fhdup    ::dup
+#define fhdup2   ::dup2
+#define fhfdopen ::fdopen
+#define fhfileno ::fileno
+#endif
+
+int llfd::close(int fd)
+{
+    return fhclose(fd);
+}
+
+int llfd::dup(int target)
+{
+    return fhdup(target);
+}
+
+int llfd::dup2(int target, int reference)
+{
+    return fhdup2(target, reference);
+}
+
+FILE* llfd::open(int fd, const char* mode)
+{
+    return fhfdopen(fd, mode);
+}
+
+int llfd::fileno(FILE* stream)
+{
+    return fhfileno(stream);
+}
+
+/*****************************************************************************
+*   LLTempRedirect
+*****************************************************************************/
+LLTempRedirect::LLTempRedirect():
+    mOrigTarget(-1),                // -1 is an invalid file descriptor
+    mReference(-1)
+{}
+
+LLTempRedirect::LLTempRedirect(FILE* target, FILE* reference):
+    LLTempRedirect((target?    fhfileno(target)    : -1),
+                   (reference? fhfileno(reference) : -1))
+{}
+
+LLTempRedirect::LLTempRedirect(int target, int reference):
+    // capture a duplicate file descriptor for the file originally targeted by
+    // 'reference'
+    mOrigTarget((reference >= 0)? fhdup(reference) : -1),
+    mReference(reference)
+{
+    if (target >= 0 && reference >= 0)
+    {
+        // As promised, force 'reference' to refer to 'target'. This first
+        // implicitly closes 'reference', which is why we first capture a
+        // duplicate so the original target file stays open.
+        fhdup2(target, reference);
+    }
+}
+
+LLTempRedirect::LLTempRedirect(LLTempRedirect&& other)
+{
+    mOrigTarget = other.mOrigTarget;
+    mReference  = other.mReference;
+    // other LLTempRedirect must be in moved-from state so its destructor
+    // won't repeat the same operations as ours!
+    other.mOrigTarget = -1;
+    other.mReference  = -1;
+}
+
+LLTempRedirect::~LLTempRedirect()
+{
+    reset();
+}
+
+void LLTempRedirect::reset()
+{
+    // If this instance was default-constructed (or constructed with an
+    // invalid file descriptor), skip the following.
+    if (mOrigTarget >= 0)
+    {
+        // Restore mReference to point to mOrigTarget. This implicitly closes
+        // the duplicate created by our constructor of its 'target' file
+        // descriptor.
+        fhdup2(mOrigTarget, mReference);
+        // mOrigTarget has served its purpose
+        fhclose(mOrigTarget);
+    }
+    // assign these because reset() is also responsible for a "moved from"
+    // instance
+    mOrigTarget = -1;
+    mReference  = -1;
+}
+
+LLTempRedirect& LLTempRedirect::operator=(LLTempRedirect&& other)
+{
+    reset();
+    std::swap(mOrigTarget, other.mOrigTarget);
+    std::swap(mReference,  other.mReference);
+    return *this;
+}